The spinal column is a highly complex system of bones and connective tissues that provide support for the body and protect the delicate spinal cord and nerves. The anterior side of the spinal column includes a series of vertebral bodies stacked one atop the other. Situated between each vertebral body is an intervertebral disc that cushions and dampens compressive forces exerted upon the spinal column and permits motion between the vertebra. The posterior side of the spinal column includes different bony structures (e.g. lamina, pedicles, transverse processes, spinous processes, facets) that extend from the vertebral bodies and together form an arch around the spinal canal and protect the spinal cord. The adjacent vertebrae are coupled to each other along the posterior column via bilateral facet joints.
There are many types of spinal column disorders including scoliosis (abnormal lateral curvature of the spine), excess kyphosis (abnormal forward curvature of the spine), excess lordosis (abnormal backward curvature of the spine), spondylothesis (forward displacement of one vertebra over another), and other disorders caused by abnormalities, disease or trauma, such as ruptured or slipped discs, degenerative disc disease, fractured vertebra and the like. Patients that suffer from such conditions may experience a wide range of symptoms including, but not limited to, pain (often extreme and debilitating), and diminished nerve function.
To eliminate or reduce the pain associated with the various conditions noted above surgical intervention is often necessary. Often, the goal of the surgical procedure is to reduce impingement of nerves and or the spinal cord by restoring height to disc space, correcting misalignments between the vertebra, and/or correcting instability. Generally the vertebra of the affect motion segments are also fused together to prevent a return to the abnormal state. Spinal fixation systems are often used during the spinal fusion procedures to temporarily eliminate motion and secure a spinal motion segment in place until sufficient bone growth occurs to fuse the vertebrae together. More recently these fixation systems have been deployed through minimally invasive means that allow correction without creating large open exposures. While these spinal fusion procedures and minimally invasive pedicle screw fixations have a high rate of success, many existing surgical techniques are limited by the extent to which they can correct disc height and/or sagittal and/or coronal deformity. In order to achieve the optimal sagittal and/or coronal deformity correction, a facet release coupled with a spinal fixation construct is often necessary. Previous surgical procedures involving a facet release have been done using a midline incision which is dissected away from the spine to expose the facet (e.g. as is done during a posterior lateral interbody fusion PLIF).
The instruments, tools, and techniques described herein are directed towards reducing these challenges and others associated with posterior spinal fixation.